Humility is attractive. At the Rosebud Diner in Somerville, the owners gave me the full squeeze, with photos, newspaper clippings, and awards going back to the 1940s. At Leo’s Diner, I’ve been asking co-owner Richie Bezjian for personal stories for 20 minutes before he offers up this gem:

“Ben Affleck got us on Oprah. And Katie Couric.”

What? Could you back up and explain that?

Leo’s Diner is Harvard Square’s oldest restaurant, founded in 1949 by Charlie, the guy behind Charlie’s Kitchen. Through high school in the late 1970s, Richie and his brother and co-owner Raffi worked nearby in a coffeehouse with live music, and decided to stay in the business. Then one day, the bread delivery man — like hairdressers, they know all the gossip! — mentioned that the owner of Leo’s Diner wanted to retire. But at ages 21 and 23, the brothers Bezjian hardly had the experience or the money to take over.

So of course they did anyway, with Leo taking a big chance on them and taking part of the buyout as debt. That was 1982, and they decided as a thank you to keep the name. “It’s also my Zodiac sign,” Ritchie says.

I’ve lived in Cambridge since the 1980s, and I have to confess that I’ve never noticed Leo’s Diner before. It’s easy to confuse with the bar next door, because they share the same building and basic appearance. It doesn’t help that Leo’s has bottles in their window (which turn out to be root beer) and some window art that’s grassrooty but doesn’t jump out at you. With the narrow sidewalks in Harvard Square, competitive signage all around, and us Bostonians walking quickly and staring straight ahead, it would be easy to pass by.

Inside, there’s only stool seating, along the wall, the window, and the open kitchen. So it would be awkward to chat with a friend, but you’re oriented right in to chat with Richie as he cooks. Perhaps that’s why it’s so easy to engage with the staff. “We’re like a family,” Richie says. “We get to know our customers, and sometimes we get the 3rd or 4th generation of our original customers coming in here.” Richie tells me that one customer in his mid-80s says he’s never had a bad meal here. Classic rock plays on the loudspeakers.

Looking around, the diner is well-lit and bright, with a welcoming decor that includes celebrity photos on the wall, but it doesn’t look especially unique. Can it be that well-loved?

Apparently. Richie is good friends with Tom Magliozzi, the co-host of NPR’s Car Talk radio show, which is based in Cambridge. “He comes by a lot,” Richie says. “My brother and me, we’re the same way, always joking around and insulting each other.” As proof there’s a photo on the wall and one of the meals is named Click & Clack’s Noise Pollution. It’s a cheeseburger.

Richie also runs through a list of celebrities I’ve never heard of, but if you’re big into music or hockey, you’ll know the names, I’m sure.

This is when he tells me about Ben Affleck.

You’re kidding, I say.

“No really,” Richie replies. “I watched Ben & Matt grow up, I know their families.” When Ben Affleck did a celebrity segment on Oprah about his hometown, he brought the TV crew here. His favorite dish is the double cheeseburger plate. “Then he went behind the counter to cook it, which was a disaster of course,” Richie says, smiling. Then in 2004, then when the Democratic National Convention came to Boston, Katie Couric was in town to cover it, and Ben Affleck brought her here, too.

While I’m still reeling from this information, Richie tells me about the food as though nothing is out of the ordinary. “I take pride in what I do,” he says. Pointing to the open kitchen, he says, “Everything is cooked right in front of you and we don’t own a microwave.” They make their own recipes and don’t buy anything frozen. They make their own soups and salads from scratch and offer unique foods like a yogurt-based chicken rice soup with mint, a red lentil soup with asparagus, carrot, and garlic. “And we make homemade gazpacho. Who does that these days?” he says.

The theme of the diner is all-American, or Mediterranean. Or just Diner, since the napkins are very thin and water is served unceremoniously in a paper cup. The bathroom in the basement is clean but it’s fallen into disrepair, and it looks like the last renovation was an amateur job some time ago. While Leo’s Diner is very much a breakfast and lunch place, you could catch an early dinner here before they close at 7pm.

So! Let’s eat. Richie cooks and serves up several plates while I look around wondering how much time I’d have to spend eating here to be around the next time someone famous comes in.

The Unique Dominique ($9.25) is a “Broiled BBQ chicken topped with cheddar cheese, sauteed onions, & peppers.” It’s hearty, with a simple, thick slab of chicken, but the bread is plain and there’s nothing distinctive about the presentation or sauce. I wouldn’t be happy paying $9.25 for a sandwich of this quality or size.

The Steak Plate ($7.95 plain) is much better. Richie cuts the steak himself from flank meat, and the small pieces are delicious, with no gristle or fat. Although the french fries, cheese, and roll it’s served on are basic — the meal is joyous and archetypical of the “diner” experience. It’s filling and not greasy, but still, with onions, green peppers and cheese, it comes to $10 and is on the small side.

The first meal that got my attention was the Challah Bread French Toast ($6.25), with a great smell of cinnamon & powdered sugar. It’s served with a (unfortunately small portion of) real fruit, and is solid, managing to avoid that sicky, overpowering egg taste. It’s good but not a wow.

I very much approve of the Mediterranean Omelet ($7.25). The price is right and it comes with hash browns and toast, which, although ordinary, at least they’re not greasy. The omelet itself is really good, the best thing I tried at Leo’s Diner. It’s got powerful ingredients: moist tomato, salty and pure olives, and despite the egg, with the toppings mixed in it avoids being too heavy.

As for the Diego’s Salad ($9.25), you don’t even have to eat it to tell that it is glorious. Although the chicken was dry, there’s enough meat to make it a real meal, and the feta cheese and crisp lettuce make it interesting. It doesn’t need dressing, and comes with only the thinnest sprinkling of Italian. Still, this is an $8 salad.

The only item I tried that I didn’t care for was the yogurt based chicken rice soup. It was refreshingly hot, but too salty, even before I added the saltines served on the side.

Every restaurant owner tells me that he has a welcoming environment and the best, freshest food. At Leo’s Diner, I’ll take the former. While the food is priced “restaurant” but sometimes falls to “diner” quality, I can tell from the traffic in and out that the people who eat here really have formed a small community.

I get it. Leo’s Diner simply isn’t outstanding, but if you make friends with the staff, you become loyal for life. If you are a tourist looking for a local to chat with a Harvard Square regular hoping to make friends, you’ll get more attention here than at the bustling Mr. Bartley’s around the corner, in an environment that is more cheerful than Grendel’s Den down the street, which has the dark and heavy feel of a bar. Leo’s Diner is “real”, unlike so many corporately sanitized places around. I’ll give it a solid though average rating in our Pub/Cafe tier (not the ‘restaurant’ tier, see our ratings).

And who knows? Become a regular and perhaps Ben Affleck will walk in with another TV crew.